<div class="button__holder">
    <h2>Hover me &rarr;</h2>
    <button class="plus"></button>
</div>

@import url(https://fonts.googleapis.com/css?family=Source+Sans+Pro:300);

body,html{
    margin: 0;
    width: 100vw;
    height: 100vh;
    font-family: "Source Sans Pro" sans-serif;
}
.button__holder{
    position: relative;
    width: 100%;
    height: 100%;
    display: flex;
    flex-wrap: wrap;
    align-items: center;
    justify-content: center;
    background-color: #1a1a1a;
    &:after{
        content: "";
        position: absolute;
        z-index: 0;
        top: 0; right: 0; bottom: 0; left: 0;
        background: rgba(#1a1a1a, 0.7);
    }
    h2{
        margin: {right: 1em;}
        text-align: center;
        color: #8A3B58;
    }
}
.plus{
    position: relative;
    z-index: 1;
    width: 80px;
    height: 80px;
    color: #1a1a1a;
    background: #ed1c5b;
    border-radius: 50%;
    border: none;
    transition: box-shadow 400ms cubic-bezier(.2,0,.7,1), transform 200ms cubic-bezier(.2,0,.7,1);
    &:after{
        content: "+";
        font-size: 2.5em;
        line-height: 1.1em;
    }
    &:hover{
        transform: rotate(45deg);
        box-shadow: 0 0 1px 15px rgba(#8A3B58, 0.4),
        0 0 1px 30px rgba(#8A3B58, 0.1),
        0 0 1px 45px rgba(#8A3B58, 0.1);
    }
}